Neurosurgery

Intracranial Dynamics

Basic Principles

1. Fixed Cranial Volume (Monro-Kellie Doctrine)

   • The cranial cavity has a fixed volume composed of:
     • Brain tissue (parenchyma)
     • Cerebrospinal fluid (CSF)
     • Blood vessels with intravascular blood
   • Monro-Kellie Doctrine: The sum of these components is constant
     • An increase in one component must be accompanied by an equal decrease in one or both of the remaining components to maintain constant intracranial pressure (ICP)
     • Without compensation, ICP will rise, leading to decreased blood flow and oxygen delivery
   • Compensation Stage: Volume reduction in one or more compartments to avoid ICP elevation

   • Excess Volume Syndromes: Specific treatments summarized in Table 68.1

     

2. CSF Production and Dynamics

   • CSF is produced at a constant rate (~15–20 mL/h) by the choroid plexus of the ventricles
   • CSF production is minimally affected by increased ICP
     • Impaired CSF absorption or flow can exacerbate ICP effects in CNS diseases
     • Continued CSF production even at lethal ICP levels
   • Exceptions:
     • Excess CSF production: Rare choroid plexus papilloma
     • Decreased CSF production: Seen with ventriculitis

3. Cerebral Blood Flow (CBF) and Autoregulation

   • CBF varies widely (30–100 mL/100 g of brain tissue per minute) based on metabolic demand

   • Brain vasculature matches blood flow to tissue demand via autoregulation

     • Maintains needed CBF despite systemic blood pressure variations

     • Factors affecting autoregulation:

       • Arterial Pco₂ levels: Elevated or decreased levels shift autoregulation curve
       • Traumatic brain injury: Curve becomes more pronounced; small changes affect CBF dramatically (Fig. 68.1)

       

   • Oxygen Extraction Increase:

     • Occurs when tissue demand exceeds autoregulation or CBF declines
     • Dysfunction Threshold: CBF levels below 0.25 mL/g/min
     • Reversible Ischemia: CBF between 0.15 and 0.20 mL/g/min
     • Infarction: CBF between 0.10 and 0.15 mL/g/min (Fig. 68.2 not provided)
   • After Traumatic Brain Injury:
     • Metabolic oxygen consumption decreases to 0.6–1.2 μmol/mg/min
     • Complete loss of blood flow leads to infarction within minutes
     • Swelling of infarcted tissue peaks in days, resolves over weeks
   • Cascading Injury and Elevated ICP
   • Swelling of injured tissue can cause a vicious cycle:
     • Elevated ICP reduces cerebral perfusion pressure (CPP)
     • Reduced CPP decreases CBF, leading to further tissue injury
   • Decompensation Stage:
     • Brain edema leads to further ICP increases
     • Autoregulation capacity exceeded or damaged
     • CBF becomes directly linked to CPP
   • Management Goals:
     • Maintain CPP between 60–70 mm Hg
     • Keep ICP below 22 mm Hg
     • Avoid routinely using pressors to keep CPP >70 mm Hg due to systemic complications
   • Focal Mass Effect and Herniation Progression
   • Cranial Anatomy:
     • Falx cerebri and tentorium cerebelli divide the cranial cavity
     • Incisura: Only passage between supratentorial and infratentorial compartments
     • Foramen magnum: Only sizable opening apart from cranial nerves and arteries
   • Progression of Expanding Mass Lesion (e.g., acute epidural hematoma):
     1. Focal distortion only
     2. Effacement of gyri and sulci
     3. Compression of the lateral (or other) ventricle
     4. Midline shift
     5. Subfalcine herniation
     6. Temporal lobe tentorial herniation
     7. Third nerve compression (unilateral dilated pupil)
     8. Obliteration of basal cisterns
     9. Midbrain compression
     10. Midbrain infarction, Duret hemorrhages (both pupils dilate)
     11. Further brainstem compression
     12. Loss of brainstem reflexes: Progression from flexor to extensor posturing, loss of vestibuloocular, oculocephalic, and corneal reflexes
     13. Medullary compression syndrome: Affects respiratory and vasomotor reflexes, Cushing reflex (elevated systolic BP, widened pulse pressure, bradycardia)
     14. Foramen magnum herniation
   • Variations in Compliance:
     • Young patients: Low compliance; ICP rises with small mass increases
     • Patients with cerebral atrophy: Tolerate larger masses with less ICP elevation

Cerebrovascular Disorders

Overview

• Cerebrovascular disorders include congenital, acquired, and idiopathic conditions.

Arteriovenous Malformations (AVMs)

• Definition: Abnormal collection of vessels where arterial blood flows directly into veins without capillaries
• Characteristics:
  • Congenital lesions that may enlarge with age
  • Progress from low-flow to high-flow lesions
  • Prevalence: 15–18 per 100,000
  • Risk of hemorrhage: Up to 4% per year; increased risk after initial bleed
• Presentation:
  • Headaches
  • Neurologic deficits
  • Seizures

• Diagnosis:

  • CT and MRI to visualize lesion (Fig. 68.4)

  

  • Catheter angiography for vascular anatomy
  • Treatment Options:
  • Surgical resection
  • Embolization
  • Stereotactic radiosurgery (SRS)
    • Best for compact lesions <2.5 cm
    • May take up to 3 years for AVMs to shut down post-SRS
  • Spetzler-Martin Grading System used for treatment planning (Table 68.2)
    • Grades 1 & 2 = Operate
    • Grades 3 = Operate / Endovascular
    • Grade 4 & 5 = Endovascular Embolisation with Glue / Onyx

  

Cavernous Malformations

• Definition: Well-circumscribed, benign vascular lesions of thin-walled sinusoidal channels
• Prevalence: Approximately 0.5%
• Forms: Three familial forms
• Presentation:
  • Hemorrhage
  • Headaches
  • Seizures
• Diagnosis:
  • MRI - Diffusion Weighted shows characteristic dark hemosiderin ring
• Treatment:
  • Seizure control
  • Surgical excision
  • Radiosurgery to decrease bleeding rate

Capillary Telangiectasia

• Definition: Vascular channels similar to dilated capillaries with intervening brain tissue

• Characteristics:

  • Often clinically silent
  • Generally not evident on imaging
  • Not visible on conventional angiography unless large

  

• Management:

  • Typically not treated surgically

Developmental Venous Anomaly (Venous Angioma)

• Definition: Abnormal venous drainage system converging on an enlarged outflow channel

• Characteristics:

  • Poorly collateralized venous bed
  • Abnormal venous drainage may cause degenerative brain changes
  • Typical appearance of a Hydra with radially converging veins.

  

• Management:

  • Surgical removal not recommended due to risk of venous infarction

Traumatic Fistula

• Definition: Tear in the carotid or vertebral artery leading to fistula with surrounding venous plexus
• Types:
  • Carotid-cavernous fistula (CCF) [ Cavernous sinus ⇒ ICA]
  • Vertebral-jugular fistula
• Presentation:
  • CCF: Periorbital swelling, proptosis, scleral edema
  • Vertebral-jugular fistula: Prominent pulsatile bruit

• Diagnosis:

  • Dilation of superior ophthalmic vein on imaging (Fig. 68.5)

  

  

• Treatment:

  • Endovascular techniques:
    • Catheter advancement into fistula
    • Embolic material, coil, or detachable balloon to occlude fistula
  • Transorbital puncture if conventional routes fail

Aneurysms

Saccular Aneurysms (Berry Aneurysms)

• Definition: Saccular enlargement due to arterial wall weakening
• Prevalence: 2% in adults
• Incidence of Subarachnoid Hemorrhage: 6–8 per 100,000 annually
• Risk Factors:
  • Hypertension
  • Smoking
  • Excessive alcohol consumption
  • Genetic Factors: koreans, Marfans syndrome, ADPKD.
• Presentation:
  • "Worst headache of my life"
  • Subarachnoid hemorrhage
  • Cranial Nerve deficit : Optic nerve [due to ICA] & Occulomotor nerve [ due to Post Comm Artery]

• Diagnosis:

  • CT scan showing typical blood distribution (Fig. 68.6 not provided)

  

• Complications:

  • Rebleeding
  • Hydrocephalus (15–20% cases)
  • Cardiac events (50% of patients)
  • Vasospasm
  • Hyponatremia
  • Seizures

• Management of Complications:

  • Hydrocephalus: Treated with external ventricular drain

  • Vasospasm:

    • Hypervolemia and induced hypertension
    • Endovascular procedures
    • Pharmacologic agents

    

• Treatment Options:

  • Endovascular coiling
  • Stent-assisted coiling
  • Flow diversion stents
  • Surgical clipping
    • Now reserved for lesions not amenable to endovascular techniques

Risk Assessment and Grading

• Risk of Rupture based on size and location (Table 68.3 not provided)

• Clinical Grading Scales:

  • Hunt and Hess Scale (Table 68.4 not provided)

  

  • World Federation of Neurological Surgeons Scale (Table 68.5 not provided)

  

• Imaging Grading:

  • Fisher Scale based on CT findings (Table 68.6 not provided)

  

Spontaneous Intracerebral Hemorrhage

• Definition: Hemorrhage into brain parenchyma without trauma
• Causes:
  • Old patients = Chronic hypertension leading to degenerative changes or Amyloid
  • Young pt = Drug abuse & Vascular malformations
• Common Locations:
  • Basal ganglia (due to Charcot-Bouchard aneurysms) = typically happens in lenticulo striate artery
  • Putamen
  • Thalamus
  • Cerebellum
  • Pons
• Presentation:
  • Sudden-onset neurologic signs and symptoms
  • More likely to include headache

• Diagnosis:

  • CT scan for size, location, brain shift, hydrocephalus (Figs. 68.9A and 68.10)

  

• Management:

  • Blood pressure control to prevent rebleeding
  • Conservative management for small, well-tolerated hemorrhages
  • Observation for 5–7 days
• Surgical Intervention:
  • Considered for patients with:
    • Intermediate-sized hemorrhages
    • Accessible locations
    • Deterioration despite medical therapy
  • Surgical evacuation via craniotomy (Fig. 68.9B not provided)
  • Minimally invasive techniques under development
• Cerebellar Hemorrhage:
  • Higher risk of sudden deterioration from brainstem compression
  • Surgical evacuation more readily offered
  • Ventricular drainage may be insufficient alone

Mycotic Aneurysms

• Associated with:
  • Systemic infections (e.g., subacute bacterial endocarditis)
  • Pulmonary infections
• Characteristics:
  • Located distally in cerebral vasculature
  • Often multiple aneurysms
• Presentation:
  • May cause intracerebral hematoma
  • Subarachnoid hemorrhage possible
• Management:
  • Maximal antibiotic treatment
  • Surgical intervention may involve:
    • Arterial occlusion and resection
    • Anticipation of arterial bypass if needed

Moyamoya Disease

• Definition: Idiopathic nonatherosclerotic narrowing/occlusion of major intracranial vessels with collateral network formation
• Characteristics:
  • Usually bilateral
  • Collateral vessels give a "puff of smoke" appearance on angiography
• Forms:
  • Juvenile form: Cognitive decline, multiple infarcts
  • Adult form: Subarachnoid or basal ganglia hemorrhage

• Diagnosis:

  • Angiography

  

• Treatment:

  • Extracranial to intracranial (EC-IC) bypass:
    • Superficial temporal to middle cerebral artery bypass
    • Onlay synangiosis
  • EC-IC bypass preferred in adults
  • Synangiosis more effective in children

Dural Arteriovenous Malformations

• Definition: Abnormal communication between dural arteries and cerebral veins
• Etiology:
  • Likely acquired after dural sinus thrombosis
• Risk:
  • Lesions with cortical vein communication pose hemorrhage risk
• Treatment:
  • Endovascular techniques
  • Open surgical resection if necessary

Ischemic Strokes

• Neurosurgeon's Role:
  1. Endovascular treatment of acute stroke
     • Catheter angiography
     • Clot retrieval
     • Intraarterial clot lysis
     • Stent placement
  2. Decompressive craniectomy for severe brain swelling
     • Decreases intracranial pressure (ICP)
     • Reduces morbidity and mortality
• Endovascular Treatment:
  • Early intervention is critical
  • Recent trials show clinical utility of aggressive treatment
• Decompressive Craniectomy:
  • Indicated when:
    • Patients arrive outside treatment window
    • Catheter intervention fails
    • Fulminant brain swelling occurs
  • Procedure:
    • Bone flap removal to allow brain swelling outward
    • Bone flap replacement after swelling subsides
• Guidelines:
  • Evolving regarding use and effectiveness of decompressive craniectomy

Vein of Galen Malformation

• Embryological venous remnant distal to brainstem
• Presents in Childhood with Cardiac failure
• Treatment = Embolisation

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Central Nervous System Tumors

Intracranial Tumors

• Classification:
  • Primary vs. Secondary:
    • Primary tumors: Arise from tissues within the nervous system.
    • Secondary tumors: Originate outside the nervous system and metastasize to the brain.
  • Pediatric vs. Adult
  • By Cell of Origin
  • By Location in the nervous system
• Incidence:
  • Primary brain tumors: 23.03 per 100,000 (2011–2015).
  • Brain metastases: Between 100,000 and 240,000 cases annually.

Clinical Presentation

• Symptoms caused by:
  • Focal compression and dysfunction from the tumor.
  • Secondary consequences:
    • Increased intracranial pressure (ICP)
    • Peritumoral edema
    • Hydrocephalus
• Factors influencing symptoms:
  • Rate of growth
  • Tumor location
• Common symptoms:
  • Headache:
    • Occurs in 50–60% of primary brain tumors.
    • Worse in the morning due to hypoventilation during sleep.
  • Seizures:
    • May be the first symptom.
    • New-onset seizures in patients >20 years old warrant investigation for a brain tumor.
• Specific presentations by location:
  • Infratentorial lesions:
    • Headache, nausea, vomiting
    • Cerebellar signs, vertigo
    • Cranial nerve deficits

  • Supratentorial lesions:

    • Frontal lobe: Personality changes, dementia, hemiparesis, dysphasia.
    • Temporal lobe: Memory changes, auditory/olfactory hallucinations, contralateral quadrantanopia.
    • Parietal lobe: Motor/sensory impairment, apraxia, homonymous hemianopia.
    • Occipital lobe: Visual field deficits, alexia.

    

Imaging Studies

• Initial workup:
  • Computed Tomography (CT) Scan:
    • Evaluates brain density changes, calcifications, acute hemorrhage, skull lesions.
• Magnetic Resonance Imaging (MRI):
  • Modality of choice for diagnosis, surgical planning, and monitoring.
  • Gadolinium contrast enhancement:
    • Detects defects in the blood-brain barrier.
    • Localizes small metastases (up to 5 mm).
  • Advanced MRI techniques:
    • Diffusion-weighted imaging: Differentiates gliomas from abscesses.
    • Perfusion-weighted imaging: Predicts response to radiotherapy in low-grade gliomas.
    • Functional MRI: Assists in surgical planning near eloquent brain areas.
    • Diffusion tensor imaging: Demonstrates tumor effects on white matter tracts. [ pyramidal, corticospinal etc]
    • MR Spectroscopy: Chemical shift imaging = Glioma has elevated choline peak, Meningioma’s have elevated alanine peak.
  • Magnetic Resonance Angiography:
    • Evaluates tumor vascularity and relationship to normal vasculature.

Surgery

• Preoperative management:
  • Dexamethasone:
    • Reduces peritumoral edema.
  • Antiepileptic drugs:
    • Recommended for patients with seizures or tumors near the sensorimotor strip.
    • Generally not recommended for prophylaxis.
• Technical advances:
  • Intraoperative microscope: Superior illumination and magnification.
  • Cavitational ultrasonic surgical aspirator: Breaks up and removes tumors while sparing vital structures.
  • Intraoperative ultrasonography: Real-time imaging of tumors and cysts.
  • Intraoperative CT or MRI: Enables on-table imaging of resection extent (Fig. 68.11A not provided).
  • Image-guided frameless surgical navigation: Accurate localization during craniotomy (Fig. 68.11B not provided).
• Goals of surgery:
  • Histologic diagnosis
  • Reduction of mass effect
  • Maximal safe tumor removal
• Decision factors:
  • Needle biopsy vs. Radical resection depends on:
    • Tumor location and size
    • Sensitivity to radiation or chemotherapy
    • Patient's Karnofsky performance score
    • Systemic status of primary cancer (for metastases)

Primary Brain Tumors

• Divided into:
  • Intraaxial tumors: Arise within brain parenchyma.
  • Extraaxial tumors: Arise outside brain parenchyma.

Intraaxial Brain Tumors

Gliomas

• Develop from glial cells.
• Types:
  • Astrocytic tumors
  • Oligodendrogliomas
  • Ependymomas
• Characteristics:
  • Infiltrate widely along white matter tracts.
  • Rarely totally resectable.
• Treatment options vary by histology.

Astrocytic Tumors

Glioblastoma Multiforme (WHO Grade IV)

• Most common primary brain tumor in adults.
• Presentation:
  • Headache, seizures, focal deficits, personality changes.
• Imaging:
  • Ring-enhancing lesion with surrounding edema (Fig. 68.12 not provided).
• Treatment:
  • Gross total resection
  • Postoperative radiation therapy
  • Chemotherapy:
    • Temozolomide improves survival and quality of life.
• Recurrence is common; repeat surgeries may be necessary.

Anaplastic Astrocytoma (WHO Grade III)

• Similar presentation to glioblastoma multiforme.
• Treatment:
  • Surgical resection
  • Radiation therapy
  • Chemotherapy
• Prognosis:
  • Slightly better than glioblastoma multiforme (Fig. 68.13 not provided).

Pilocytic Astrocytoma (WHO Grade I)

• Typically occurs in children.
• Locations:
  • Posterior fossa: Causes obstructive hydrocephalus, cerebellar signs.
  • Hypothalamus or optic tract: Different management.
• Treatment:
  • Surgical resection (posterior fossa lesions).
  • Biopsy and chemotherapy/radiation (hypothalamic/optic lesions).

Oligodendroglioma

• Origin: Oligodendroglial cells.
• Prevalence: 25% of all glial tumors.
• Demographics:
  • Male predominance (3:2).
  • Average age: 40 years.
• Presentation:
  • Seizures, hemorrhage, mass effect.
• Survival:
  • 5-year survival rate: 40–70%.
  • Median survival: 3 years.
• Treatment:
  • Surgical resection
  • Chemotherapy:
    • Favorable response if 1p and 19q chromosomal losses are present.
  • Radiation therapy for anaplastic forms.

Ependymoma

• Incidence: 5% of intracranial gliomas.
• Peak age: 10–15 years.
• Common locations:
  • Children: Floor of the fourth ventricle.
• Presentation:
  • Symptoms of hydrocephalus, increased ICP.
• Prognosis:
  • 80% 5-year survival in young patients.
  • Poor prognosis for anaplastic variants.
• Treatment:
  • Maximal surgical resection
  • Fractionated radiation therapy
  • Spinal MRI and CSF cytology to check for metastases.

Choroid Plexus Papilloma and Carcinoma

• Incidence: 1% of intracranial tumors.
• Demographics:
  • 70% occur in children under 2 years.
• Presentation:
  • Hydrocephalus due to CSF overproduction.
• Prognosis:
  • Papillomas: 85% 5-year survival.
  • Carcinomas: 40% 5-year survival.
• Treatment:
  • Total surgical excision
  • Adjuvant chemotherapy (carcinomas)
  • Radiation therapy (for carcinomas)

Pediatric Brainstem Gliomas

• Incidence: 10–20% of pediatric brain tumors.
• Mean age: 7 years.
• Types:
  • Midbrain gliomas (tectal and tegmental):
    • Better survival rates.
    • Tectal gliomas: Present with hydrocephalus.
  • Diffuse pontine gliomas:
    • Present with cranial nerve palsies, ataxia.
    • Poor prognosis (<1-year median survival).
• Treatment:
  • Tectal gliomas:
    • Vigilant follow-up.
    • CSF diversion/shunting.
  • Focal tegmental tumors:
    • Possible surgical resection.
    • Chemotherapy and radiation if recurrent.
  • Diffuse pontine gliomas:
    • Radiation therapy.
    • Experimental chemotherapy or palliative care.

Neuronal and Mixed Neuronal-Glial Tumors

Ganglioglioma and Gangliocytoma

• Incidence: <12% of intracranial tumors.
• Demographics:
  • Peak at 11 years old.
• Presentation:
  • Seizures
• Prognosis:
  • 80–90% survival at 5–10 years.
• Treatment:
  • Complete surgical resection
  • Radiation therapy for anaplastic variants.

Central Neurocytoma

• Incidence: ~10% of intraventricular tumors.
• Demographics:
  • Ages 20–40 years.
• Presentation:
  • Hydrocephalus, increased ICP, seizures.
• Prognosis:
  • 80% survival.
• Treatment:
  • Complete resection
  • Stereotactic radiosurgery (SRS) or chemotherapy if recurrence occurs.

Dysembryoplastic Neuroepithelial Tumor

• Incidence: <1% of primary brain tumors.
• Demographics:
  • Primarily affects children and young adults (<20 years).
• Presentation:
  • Seizures
• Treatment:
  • Surgical resection
  • Removal of epileptogenic foci if necessary.

Paraganglioma

• Presentation:
  • Slow-growing mass
  • Catecholamine release symptoms: Carcinoid-like syndrome.
  • Cranial nerve palsies
• Types (based on location):
  • Carotid body tumor
  • Glomus jugulare tumor
  • Glomus tympanicum
  • Glomus intravagale
  • Pheochromocytoma
• Treatment:
  • Medical therapy: Alpha and beta blockers.
  • Surgical resection
  • Embolization to reduce blood loss.
  • Radiation therapy if surgery is not feasible.

Pineal Region Tumors

Pineocytoma

• Incidence: <1% of primary brain tumors.
• Demographics:
  • Peak between 10–20 years.
• Presentation:
  • Hydrocephalus
  • Increased ICP
  • Parinaud syndrome (vertical gaze disturbance).
• Prognosis:
  • 90% 5-year survival.
• Treatment:
  • Surgical removal if symptomatic or enlarging.

Pineoblastoma

• Incidence: <1% of brain tumors.
• Demographics:
  • Peak at 3 years old.
  • Predominantly females (2:1 ratio).
• Presentation:
  • Similar to pineocytoma.
  • CSF seeding in 50% of cases.
• Prognosis:
  • Median survival: 2 years.
• Treatment:
  • Surgical resection
  • Craniospinal irradiation
  • Chemotherapy for patients over 3 years old.

Papillary Tumor of the Pineal Region

• Rare tumor in children and young adults.
• Behavior:
  • Grade II or III tumor.
  • Can recur.
• Treatment:
  • Surgical resection
  • Focal irradiation

Primitive Neuroectodermal Tumors

Medulloblastoma

• Incidence:
  • 15–20% of brain masses in children.
  • One-third of posterior fossa tumors.
• Demographics:
  • Diagnosed by age 5.
  • Male predominance (3:1).
• Presentation:
  • Hydrocephalus
  • Increased ICP
  • Cerebellar signs
  • CSF dissemination common.
• Treatment:
  • Gross total resection
  • Adjuvant chemotherapy and radiation (if over 3 years old).

Tumors of Cranial and Spinal Nerves

Schwannoma

• Incidence: ~8% of intracranial tumors.
• Types:
  • Intracranial schwannomas: Present with seizures or focal deficits (<30 years old).
  • Vestibular schwannomas: Sensorineural hearing loss, tinnitus, dizziness (>30 years old).

• Association:

  • Bilateral vestibular schwannomas indicate neurofibromatosis type 2.

  

  Characteristic = ICE CREAM CONE appearance

• Treatment:

  • Observation for small tumors (<3 cm).
  • Stereotactic radiosurgery (SRS) for growing tumors (<3 cm).
  • Surgical resection:
    • Tumors >3 cm.
    • Risks: Hearing loss, facial palsy.

Neurofibroma

• Rare intracranially; associated with neurofibromatosis type 1.
• Locations:
  • Orbit, scalp, parotid gland.
  • Spinal canal: Dumbbell-shaped masses.
• Presentation:
  • Painless mass
  • Slow growth
• Risk:
  • 2–12% may become malignant peripheral nerve sheath tumors.
• Treatment:
  • Surgical resection:
    • May require nerve sacrifice.

Tumors of the Meninges

Meningiomas

• Incidence: 15–20% of primary intracranial tumors.
• Demographics:
  • Female predominance (2:1).
  • Rare in childhood unless associated with neurofibromatosis type 1. DT class = typically associated with NF -2 ? ? ?

• Presentation:

  • Often incidental (up to 50%).
  • Slow-growing

  

• Prognosis:

  • 90% 5-year survival.
• Treatment:
  • Surgical resection if symptomatic.
  • Observation for small, asymptomatic tumors.
  • RT

• Recurrence depends on:

  • Extent of resection (Simpson grading system).

  

  • Histology (atypical or malignant variants).
    • grade 1= surgery is enough
    • grade 2 & 3 = surgery + RT [ CT is not helpful]

Hemangioblastoma

• Incidence: 1–2% of primary intracranial tumors.
• Association:
  • 25–40% with von Hippel–Lindau syndrome.
• Presentation:
  • Posterior fossa mass effect
  • Cyst expansion
• Treatment:
  • Surgical resection
• Prognosis:
  • 85% 10-year survival.
  • 15% recurrence rate.

Lymphomas and Hematopoietic Tumors

Primary Central Nervous System Lymphoma

• Incidence:
  • Increased to 10% of primary intracranial tumors.
  • 2–6% in patients with AIDS.
• Demographics:
  • Mean age: 60 years (immunocompetent), 35 years (immunodeficient).
• Presentation:
  • Mass effect symptoms.
  • Neuropsychiatric changes.
• Prognosis:
  • Median survival: 1–4 months (untreated), 1–4 years (treated).
• Treatment:
  • Stereotactic biopsy
  • Radiation therapy
  • Chemotherapy (methotrexate-sensitive)
  • Intrathecal methotrexate for young patients.

Plasmacytoma

• Location: Usually involves the skull.
• Risk:
  • High risk of developing multiple myeloma within 10 years.
• Treatment:
  • Rule out systemic multiple myeloma.
  • Complete surgical excision
  • Radiation therapy

Germ Cell Tumors

Germinoma

• Incidence: 1–2% of primary CNS tumors.
• Common locations:
  • Pineal region (50%).
• Demographics:
  • Peak age: ~10 years.
  • Male predominance (pineal region), female predominance (suprasellar region).
• Presentation:
  • Hydrocephalus, Parinaud syndrome (pineal region).
  • Hypothalamic-pituitary dysfunction, visual decline (suprasellar region).
• Prognosis:
  • 90% 5-year survival.
• Treatment:
  • Biopsy
  • Radiation therapy and chemotherapy
  • Hydrocephalus management

Nongerminomatous Germ Cell Tumors

• Types:
  • Embryonal carcinoma
  • Yolk sac tumors
  • Choriocarcinomas
  • Teratomas
• Demographics:
  • Often found in infants and adolescents.
• Prognosis:
  • Generally worse than germinomas (<50% 5-year survival).
• Treatment:
  • Resection plus chemotherapy and radiation.
  • Treatment algorithms vary; no significant survival difference noted.

Tumors of the Sellar Region

Pituitary Adenomas

• Incidence: 10% of intracranial tumors.
• Demographics:
  • Peak in 3rd and 4th decades.
• Presentation:
  • Hormone-producing tumors: Most Common = Early symptoms due to hormonal effects.
  • Nonfunctioning adenomas: Symptoms due to mass effect. = Bitemporal hemianopia
• Treatment:
  • Endocrine evaluation
  • Surgical options:
    • Transsphenoidal approach
    • Open craniotomy for large tumors.
  • Radiation therapy for refractory cases.

Types of Pituitary Adenomas and Treatment

• Prolactinoma:
  • Symptoms: Amenorrhea, galactorrhea, impotence, infertility.
  • Prolactin Levels:
    • Normal = 25 ng/ml
    • Stalk Effect = 25-150 ng/ml
    • Prolactinoma = >150 ng/ml [>100 ng/ml ⇒ suspicious of Prolactinoma]
  • Treatment: Dopamine agonists (e.g., bromocriptine).
• Adrenocorticotropin adenoma:
  • Symptoms: Cushing disease features.
  • Treatment: Surgery.
• Growth hormone-secreting tumors:
  • Symptoms: Acromegaly, gigantism.
  • Treatment: Surgery, possible octreotide therapy.
• Thyroid-stimulating hormone-secreting tumors:
  • Symptoms: Hyperthyroidism, anxiety, palpitations.
  • Treatment: Surgery.
• Gonadotropin-secreting and nonfunctional adenomas:
  • Symptoms: Mass effect, bitemporal hemianopia, cranial nerve deficits.
  • Treatment: Surgical resection.

Craniopharyngiomas

• Incidence: 2–5% of intracranial tumors.
• Demographics:
  • 50% in children (peak between 5–10 years).
• Presentation:
  • Similar to other suprasellar masses.
  • hypothalamic dysfunction
  • hydrocephalus
• Prognosis:
  • 5-year survival: 55–85%.
  • Recurrences common within 1 year post-surgery.
• Treatment:
  • Medical optimization pre-surgery.
  • Attempted total resection.
  • Radiation therapy if subtotal resection.

Central Nervous System Metastasis

• Most common brain tumor in adults (>50% of brain tumors). [ Most Common primary = glioma]
• Incidence:
  • 6–14% of cancer patients develop brain metastases.
• Common primary sources:
  • Men: Lung cancer.
  • Women: Breast cancer.
  • short interval to mets = Lung Cancer = prophylactic craniospinal radiation.
  • Long interval to mets = Breast cancer
• Presentation:
  • Significant brain edema
  • Initial response to steroids
• Treatment considerations:
  • Solitary metastasis:
    • Total surgical excision
    • Whole brain radiotherapy
  • Multiple metastases:
    • Symptomatic lesion excision or upto 3 mets can be operated. surgery is also done for unknown primary lesion.
    • Whole brain radiotherapy
    • Stereotactic radiosurgery (SRS)
• Factors influencing treatment:
  • Patient's overall health
  • Extent of systemic disease
  • Life expectancy

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Traumatic Brain Injury

Overview

• Goal: Provide a practical approach to managing brain injuries.
• Guidelines:
  • Brain Trauma Foundation Guidelines (1995, reviewed in 2016)
  • Advanced Trauma Life Support (ATLS) by the American College of Surgeons

Epidemiology

• Incidence:
  • Between 500,000 to over 1 million cases annually
  • Most cases are mild injuries
  • Approximately 20% are moderate to severe
• Mortality:
  • 50% of the 150,000 trauma deaths yearly are due to head injury
• Impact:
  • Significant social, medical, and economic implications
• Prevention:
  • Programs are decreasing the incidence of severe traumatic brain injury

Pathophysiology

Primary Injury

• Occurs at impact
• Includes:
  • Bone fractures:
    • Cranial vault and skull base fractures indicate force of impact
    • Skull base fractures may cause:
      • Cranial nerve deficits
      • Arterial dissection
      • CSF fistula formation
    • Types of fractures:
      • Open or closed
      • Depressed or nondepressed
      • Linear or comminuted
    • May disrupt meningeal arteries or dural venous sinuses leading to intracranial bleeding
  • Intracranial hemorrhages:
    • Epidural hemorrhage:
      • Between dura and skull
      • Usually due to meningeal artery laceration from skull fracture
    • Subdural hemorrhage:
      • Between dura and arachnoid
      • Often from shearing of bridging veins
    • Subarachnoid hemorrhage:
      • Bleeding into CSF spaces
      • Trauma is the most common cause
      • Distinguished from aneurysmal rupture by history and CT distribution
    • Intraparenchymal (intracerebral) hemorrhage:
      • Bleeding into brain tissue
      • Ranges from small contusions to large clots
      • May require emergent surgical evacuation

  • Diffuse Axonal Injury:

    • Rotational acceleration-deceleration injury to white matter
    • Causes functional or anatomical disruption
    • Believed to cause loss of consciousness without mass lesions
    • Can occur with or without other injuries

    

Secondary Injury

• Results from decreased oxygen delivery
• Mechanisms:
  • Altered cerebral autoregulation
  • Systemic hypotension leading to decreased CBF
  • Intracranial hypertension further decreases CBF
  • Hypoxemia exacerbates ischemia
  • Cellular cascade:
    • Inflammation mediators
    • Excitotoxicity
    • Calcium influx
    • Na⁺,K⁺-ATPase dysfunction
    • Leads to neuronal dysfunction and death
• Prevention:
  • Prevent hypotension and hypoxia
  • Control intracranial pressure (ICP)
  • Maintain cerebral perfusion pressure (CPP)

Prehospital and Emergency Department Management

• ABCs First:
  • Airway: Secure patent airway
  • Breathing: Ensure adequate ventilation and oxygenation
  • Circulation: Maintain adequate circulation
• Avoid hypotension and hypoxia:
  • Systolic BP <90 mm Hg
  • PaO₂ <60 mm Hg
• Spine Precautions:
  • Appropriate cervical immobilization

• Neurologic Evaluation:

  • Glasgow Coma Scale (GCS):

    • Assesses: Eye opening, verbal response, motor response
    • Grades TBI as mild, moderate, or severe

    

  • Pupillary size and reactivity

  • Considerations:
    • Hypoxia, hypotension, alcohol, drugs may alter findings
    • Abnormal findings assumed to be primary brain injury until proven otherwise
  • Imaging:
  • CT Scan:
    • Evaluates for fractures, hematomas, midline shift, cisterns
  • Cervical Spine Scanning:
    • Rules out acute fractures or dislocations
  • Emergency Procedures:
  • Exploratory burr holes if immediate surgery is needed elsewhere and intracranial hematoma is suspected
  • Transfer to Higher-Level Care:
  • Follow ATLS guidelines
  • Secure airway, ventilation, circulation
  • Treat anemia with transfusion if necessary
  • Avoid hypoxia and hypotension
  • Immobilize with backboard and cervical collar
  • Consider mannitol for intracranial hypertension after neurosurgical consultation
  • Effective communication between transferring and receiving teams is crucial

Treatment

• Surgical Intervention:
  • Indicated for intracranial mass lesions causing deficits
  • Clots or contusions >30 mL are typically operable
  • Epidural and subdural hematomas treated with craniotomy
  • Intracerebral hematomas addressed via appropriate craniotomies
• ICP Monitoring:
  • Devices:
    • Intraventricular drains
    • Intraparenchymal monitors
    • Epidural or subdural devices
  • Indications:
    • GCS ≤ 8
    • Some patients with moderate TBI
• Management of Intracranial Hypertension:
  • Positioning:
    • Elevate head to 30 degrees
    • Neutral head position
    • Ensure cervical collars do not obstruct jugular venous flow
  • Goals:
    • ICP <22 mm Hg
    • CPP ≥60–70 mm Hg (CPP = MAP - ICP)
• Treatment Steps for Elevated ICP:
  1. CSF Drainage:
     • First-line therapy
     • Via external ventricular drain (ventriculostomy)
  2. Sedation and Paralysis:
     • Pharmacologic sedation to reduce ICP
     • Monitor pupils and ICP readings
     • Emergent CT scan if rapid changes occur
  3. Mannitol and Diuretics:
     • Mannitol dosage: 0.25–1 g/kg IV every 4–6 hours
     • Monitor serum osmolality
     • Maintain euvolemia
  4. Hyperventilation:
     • Temporary measure
     • Lower PaCO₂ to 30–35 mm Hg
  5. Second-Tier Therapies:
     • Hypertonic saline
     • High-dose barbiturates
     • Decompressive craniectomy
• Monitoring and Imaging:
  • Serial CT scans tailored to patient needs

Additional Considerations

• Nutrition:
  • Increased energy requirements post-TBI
  • Nonparalyzed patients: 140% of resting metabolic expenditure
  • Paralyzed patients: 100%
  • Begin feeding within 5–7 days post-injury
• Steroids:
  • Not recommended; no proven benefit
• Anticonvulsants:
  • Prophylactic use not indicated for late seizures
  • May be used to prevent early posttraumatic seizures in high-risk patients
  • Typically tapered after one week
• Hyperventilation Risks:
  • Decreases ICP but also reduces CBF
  • Monitoring CBF is recommended if PaCO₂ <30 mm Hg.

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Degenerative Disorders of the Spine

Degenerative Disease of the Lumbar Spine

Overview

• Prevalence:
  • 80% of adults experience low back pain at some point
  • Leading cause of job-related disability
  • Second most common neurologic ailment after headache
• Anatomy:
  • Lumbar spine:
    • Five lumbar vertebrae with intervertebral discs
    • Each vertebra has:
      • Anterior vertebral body
      • Posterior neural arch (pedicles, facet joints, transverse processes, laminae, spinous process)
  • Intervertebral disc components:
    1. Cartilaginous endplates: Nutrition and anchoring
    2. Annulus fibrosus: Concentric collagen sheets containing the nucleus
    3. Nucleus pulposus: Soft, semigelatinous collagen absorbing axial loads
  • Spinal cord ends at L1 level
  • Cauda equina: Lumbar and sacral nerve roots continuing distally

Degenerative Process

• Aging leads to loss of compressive load-bearing by the nucleus pulposus
• Load shifts to the annulus fibrosus, causing:
  • Fatigue failure
  • Fissuring
  • Rupture
• May result in disc herniation
• Spondylosis:
  • Osteophyte formation at vertebral endplates
• Additional stress on posterior elements causes:
  • Facet arthrosis and hypertrophy
  • Thickening and buckling of the ligamentum flavum ⇒ Lumbar Canal Stenosis

Lumbar Radiculopathy

• Disc Herniations:

  • Most commonly posterolateral
  • Compresses nerve root, causing:
    • Low back pain
    • Radicular symptoms in specific dermatomes
  • Back pain often minor compared to leg symptoms

  

• Cauda Equina Syndrome:

  • From large central disc herniations
  • Symptoms:
    • Saddle anesthesia
    • Urinary retention (possible overflow incontinence)
    • Significant motor weakness
  • Emergency decompression within 24 hours recommended

Management

• Conservative Treatment for 4–8 weeks unless urgent
  • Rest and activity modification
  • Physical therapy
  • Weight loss
  • Analgesics and muscle relaxants
  • Oral steroids
  • Epidural steroid injections
• Imaging:
  • MRI is diagnostic test of choice
  • Postmyelography CT for MRI-incompatible patients
• Surgical Treatment:
  • Standard procedure:
    • Midline approach with hemilaminectomy
    • Expose thecal sac and nerve root
    • Remove herniated fragment
  • Minimally invasive techniques:
    • 1-cm paramedian incision
    • Microscopic or endoscopic visualization
  • Outcomes:
    • Immediate relief in most patients
    • Recurrent herniation occurs in 3–19% of patients

Lumbar Spinal Stenosis

• Cause:
  • Advanced degeneration leading to:
    • Spondylosis
    • Facet hypertrophy
    • Thickened ligamentum flavum
• Results in:
  • Narrowing of spinal canal
  • Constriction of thecal sac
  • Neurologic deficits
• Presentation:
  • Neurogenic claudication:
    • Unilateral or bilateral discomfort
    • Triggered by standing, walking, prolonged posture
    • Relieved by sitting, squatting, recumbency
    • Symptoms: Pain, weakness, paresthesias
• Diagnosis:
  • Clinical history is crucial
  • MRI shows characteristic findings
• Management:
  • Nonsurgical:
    • NSAIDs, analgesics
    • Epidural steroid injections
    • Physical therapy
  • Surgical decompression:
    • Indicated for disabling pain limiting daily activity
    • Laminotomies or laminectomies with facet undercutting
    • Avoid aggressive decompression to prevent instability

Lumbar Instrumentation and Fusion

• Indications:
  • Spondylolisthesis (vertebral body slippage)
  • Recurrent herniated disc with instability
  • Chronic mechanical/discogenic back pain
  • Selected patients with degenerative disease without stenosis or spondylolisthesis
• Approaches:
  1. Posterolateral Fusion:
     • Transverse processes decorticated
     • Bone graft applied
  2. Pedicle Screw Fixation:
     • Screws in pedicles connected with a rod
     • May be combined with fusion
  3. Posterior Lumbar Interbody Fusion:
     • Intervertebral spacer inserted via laminotomy
     • Combined with instrumentation
  4. Transforaminal Interbody Fusion:
     • Facet joint removed on one side
     • Bone graft or cage inserted obliquely
     • Unilateral or bilateral fusion
  5. Anterior Lumbar Interbody Fusion:
     • Bone graft or cage placed via anterior retroperitoneal approach
     • May use a metallic interbody plate
  6. Lateral Approaches:
     • Extreme/direct/oblique lateral interbody fusion
     • With or without posterior instrumentation

Degenerative Diseases of the Cervical Spine

Overview

• Similar pathophysiology to lumbar spine
• Key Differences:
  • Cervical spinal canal contains the spinal cord
  • Compression can cause spinal cord deficits
  • Seven cervical vertebrae, eight cervical nerves

Cervical Radiculopathy

• Presentation:
  • Symptoms often upon awakening
  • Pain radiates from neck to arm
  • Numbness and paresthesia in dermatomal pattern
  • Pain worsened by neck movements
  • Possible motor weakness
• Examination:
  • Spurling Sign:
    • Pain with downward pressure and head tilt toward symptomatic side

• Affected Nerve Roots:

  • Compression of C5–C8 roots leads to specific symptoms (refer to Table 68.11)

  

Cervical Myelopathy

• Caused by:
  • Acute large disc herniation
  • Chronic osteophytic spurs from spondylosis or stenosis
• Symptoms:
  • Spasticity
  • Increased reflexes
  • Clonus
  • Babinski and Hoffman signs
  • Weakness and clumsiness in hands
• Risks:
  • Increased risk of spinal cord injury with trauma if untreated

Diagnosis and Treatment

• Diagnosis:
  • MRI is initial study of choice
  • CT Myelogram if MRI contraindicated or detailed anatomy needed
  • Electromyography and Nerve Conduction Studies to rule out other conditions
• Management:
  • Conservative Treatment:
    • Oral steroids
    • NSAIDs
    • Analgesics
    • Muscle relaxants
    • Cervical traction
    • Physical therapy
    • 90% improve without surgery
  • Surgical Indications:
    • Failure to improve with conservative measures
    • Progressive neurologic deficits
• Surgical Approaches:
  • Anterior Approach:
    • Anterior cervical discectomy, decompression, and fusion
    • Indicated for paracentral herniations or uncovertebral osteophytes
    • Access via plane between carotid sheath and tracheoesophageal complex
    • Use of operative microscope
    • Placement of bone graft and metallic plate for fusion
  • Posterior Approach:
    • Keyhole foraminotomy
    • For unilateral radiculopathy with soft disc herniation or small osteophyte
    • Small foraminotomy to decompress nerve root
• Cervical Spondylosis and Myelopathy:
  • Tailored approach based on pathology
  • Posterior Cervical Laminectomy:
    • For multiple discs or osteophytes causing myelopathy
    • May require lateral mass instrumentation and fusion
  • Complex Surgery:
    • Staged procedures for anterior and posterior compression
    • Anterior discectomies/corpectomies with reconstruction and plating
    • Followed by posterior laminectomies with lateral mass plating
  • Goal: Arrest progression of myelopathy

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Functional and Stereotactic Neurosurgery

Functional neurosurgery focuses on altering the nervous system's anatomy or physiology to achieve therapeutic effects, particularly for conditions like pain, movement disorders, epilepsy, and certain psychiatric disorders that are refractory to conventional treatments. The interventions include electrical stimulation, ablative procedures, and drug delivery systems.

Stereotactic Surgery

• Definition: A technique that allows for the precise localization of targets within the brain in three-dimensional space, facilitating interventions on deep-seated structures not directly visible during surgery.
• Methods:
  • Frame-Based Systems: Utilize a rigid frame attached to the skull, allowing for accurate targeting using Cartesian coordinates derived from imaging studies (CT, MRI).
  • Frameless Systems: Employ advanced imaging, fiducials, and reference markers without a fixed frame, often incorporating robotic arms and real-time navigation.
• Applications:
  • Brain Biopsies
  • Deep Brain Stimulation (DBS)
  • Ablative Procedures
  • Stereotactic Radiosurgery (SRS)

Stereotactic Radiosurgery (SRS)

• Overview: Delivers concentrated doses of radiation to precise intracranial targets while minimizing exposure to surrounding tissues.
• Techniques:
  • Gamma Knife: Uses cobalt-60 sources focused on a single point.
  • Linear Accelerators: Deliver radiation in multiple arcs from different angles.
• Common Uses:
  • Metastatic Brain Tumors
  • Benign Cranial Nerve Lesions
  • Arteriovenous Malformations (AVMs)
  • Trigeminal Neuralgia
• Risks:
  • Radiation Necrosis
  • Injury to Surrounding Structures

Brain Stimulation

Deep Brain Stimulation (DBS)

• Purpose: Used primarily for movement disorders like Parkinson's disease, especially in patients unresponsive to medication.
• Targets:
  • Globus Pallidus Internus - initial target of choice for parkinsons
  • Subthalamic Nucleus: Alleviates rigidity and akinesia. = present target of choice for parkinsons [ ST-AR]
  • Ventral Intermediate Nucleus of the Thalamus: Effective for tremor control. [ VIN-T]
• Advantages:
  • Adjustable and Reversible: Stimulation parameters can be modified.
  • Minimally Invasive: Avoids permanent lesions.

Spinal Cord Stimulation

• Indications:
  • Chronic Pain Syndromes
  • Dystonia
  • Bladder Dysfunction
• Procedure:
  • Initial trial with percutaneous electrodes connected to an external generator.
  • Permanent implantation if the trial is successful.

Vagus Nerve Stimulation

• Uses:
  • Intractable Epilepsy
  • Severe Depression
• Mechanism: Modulates brain activity through afferent stimulation of the left vagus nerve.

Implantable Pumps

• Function: Deliver medications directly to the cerebrospinal fluid or parenchyma.
• Common Medications:
  • Intrathecal Narcotics: For chronic pain management.
  • Baclofen: For spasticity control.
• Benefits:
  • Targeted Delivery: Reduces systemic side effects.
  • Programmable Dosing: Allows for dose adjustments based on patient needs.

Destructive Lesions

• Historical Context: Preceded the development of neuromodulation techniques.
• Procedures:
  • Dorsal Root Entry Zone Lesions: For deafferentation pain.
  • Myelotomy: Used in bilateral cancer pain.
  • Cordotomy: Lesioning of the spinothalamic tract for unilateral pain relief.
  • Sympathectomy: Interrupts sympathetic pathways for conditions like hyperhidrosis and Raynaud's disease.
  • Neurectomy: Surgical removal or interruption of peripheral nerves for pain relief.

Epilepsy Surgery

• Goal: Identify and resect the epileptogenic focus when seizures are refractory to medication.

• Evaluation:

  • Imaging: MRI and CT scans to locate lesions.
  • Functional Studies: Magnetoencephalography, PET, SPECT, and functional MRI.
  • Invasive Monitoring: Depth electrodes, grid electrodes, and the Wada test [for language dominance = Na Amobarbital].

  

• Surgical Options:

  • Anterior Temporal Lobectomy: Most common, involves resection of the anterior temporal lobe, hippocampus, and amygdala.
  • Focal Cortical Resection: Removes the specific area of seizure onset.
  • Multiple Subpial Transection: Interrupts horizontal seizure spread in eloquent cortex.
  • Corpus Callosotomy: Prevents spread of seizures in generalized epilepsy. = drop attacks and lennox gastaut sx
  • Hemispherectomy: Reserved for severe unilateral epilepsies in children. = Rasmussen Sx
• Innovations:
  • Responsive Neurostimulation (RNS): Closed-loop system that detects and disrupts seizures via cortical stimulation.

Trigeminal Neuralgia

• Characteristics: Severe, episodic facial pain affecting the trigeminal nerve divisions, often triggered by mild stimuli.
• Etiology: Commonly due to vascular [Superior Cerebellar artery] compression of the trigeminal nerve root entry zone.
• Diagnosis = Clinical
  • MRI is indicated to rule out Secondary causes
• Medical Management:
  • Carbamazepine
  • Baclofen
  • Gabapentin
• Surgical Treatments:
  • Microvascular Decompression: Relieves nerve compression by repositioning offending vessels.
  • Percutaneous Techniques:
    • Radiofrequency Rhizotomy
    • Glycerol Rhizolysis
    • Balloon Compression
  • Stereotactic Radiosurgery: Focused radiation targeting the trigeminal nerve.

Brain Death

• Irreversible loss of cerebral and brain stem function
• Diagnosis:
  • rule oute out metabolic causes of coma
  • establish irreversible coma
  • demonstrate that brain stem is not functioning = with apnea test
• No response to pain
• No respone to apnea
• Absent brain stem reflexes

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Hydrocephalus

Hydrocephalus is the enlargement of the cerebral ventricles due to an imbalance between the production and absorption of cerebrospinal fluid (CSF). It can be classified based on the nature of CSF flow disruption:

• Obstructive (Non-communicating) Hydrocephalus: Blockage within the ventricular system prevents CSF from flowing properly. It often results in the enlargement of some ventricles but not others, indicating the site of obstruction.
• Communicating Hydrocephalus: CSF flows freely through the ventricular system but is inadequately absorbed at the arachnoid granulations. This type typically shows uniform enlargement of all four ventricles.

Overproduction of CSF is a rare cause, usually due to choroid plexus tumors that produce excess CSF beyond the body's absorptive capacity.

Types and Causes

• Obstructive Hydrocephalus:
  • Often congenital.
  • Can be caused by intraventricular or periventricular masses (e.g., tumors, cysts).

• Communicating Hydrocephalus:

  • Usually acquired.
  • Common causes include infection (post-infectious hydrocephalus) and hemorrhage (post-hemorrhagic hydrocephalus).
  • Post-hemorrhagic hydrocephalus results from obstruction of arachnoid granulations by blood cells.

  

Normal-Pressure Hydrocephalus

• Definition: A type of communicating hydrocephalus where ventricular enlargement occurs without an increase in CSF pressure.
• Clinical Triad: [Hakim Adam Triad]
  1. Gait Ataxia: Difficulty in walking.
  2. Urinary Incontinence: Loss of bladder control.
  3. Dementia: Cognitive decline.
• Diagnosis:
  • Imaging shows ventriculomegaly disproportionate to brain atrophy.
• Treatment:
  • CSF Diversion (e.g., ventriculoperitoneal shunt).
  • Best outcomes when patients present with the clinical triad in the order listed above.

Hydrocephalus and Pregnancy

• Management:
  • Tailored to individual patients.
  • Symptoms of Shunt Failure:
    • Headache
    • Nausea and vomiting
    • Seizures
    • Lethargy
  • Considerations:
    • Rule out preeclampsia, which can present with similar symptoms.
    • Increased risk of distal shunt malfunction due to abdominal changes.
• Delivery:
  • Cesarean Section:
    • Prophylactic antibiotics recommended.
    • Shunt externalization may be necessary in cases of contamination.

Abdominal Surgery in Patients with Ventriculoperitoneal Shunts

• Management:
  • Individualized based on patient condition.
  • In cases of gross contamination, shunt externalization is recommended.
  • Timing of surgery and safety of simultaneous procedures are controversial; no general consensus exists.

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Pediatric Neurosurgery

Pediatric neurosurgery addresses neurological conditions in infants and children, with hydrocephalus being a common focus.

Hydrocephalus in Newborns

Presentation

• Symptoms:
  • Increased head circumference
  • Full and tense fontanelles
  • Widened cranial sutures
  • Lethargy
  • Poor feeding
  • Sunsetting eyes (impaired upward gaze)

Etiology

• Congenital Causes (typically obstructive):
  • Aqueductal Stenosis: Narrowing of the cerebral aqueduct.
  • Chiari II Malformation: Hindbrain herniation causing fourth ventricular outflow obstruction.
  • Dandy-Walker Malformation: Absence of cerebellar vermis with cystic expansion of the fourth ventricle.
  • Vein of Galen Aneurysms
  • Tumors
  • Arachnoid Cysts
• Acquired Causes (typically communicating):
  • Post-infectious: Meningitis, intrauterine infections (e.g., toxoplasmosis, cytomegalovirus).
  • Post-hemorrhagic: Intraventricular hemorrhage in premature infants.

Diagnosis

• Imaging:

  • Ultrasound: Useful in infants due to open fontanelles.
  • MRI and CT Scans: Provide detailed anatomy.

  

Treatment

• CSF Diversion:
  • Ventriculoperitoneal Shunt: Most common method.
  • Alternative Sites: Pleural cavity or superior vena cava if peritoneal cavity is unsuitable.

• Endoscopic Third Ventriculostomy:

  • Creates an opening in the floor of the third ventricle to allow CSF to bypass obstruction.
  • Suitable for obstructive hydrocephalus with functioning arachnoid granulations.

  

• Complications:

  • Shunt Infections: Occur in 5–15% of cases.
    • Management: Removal or externalization of the shunt, antibiotics, eventual replacement.

Congenital Anomalies

Myelomeningocele

• Definition: Neural tube defect with protrusion of meninges and spinal cord through a vertebral defect.
• Presentation:
  • Exposed neural tissue in a sac-like structure.
  • Neurological deficits below the lesion.
  • Associated with Chiari II Malformation and hydrocephalus.

• Treatment:

  • Surgical closure and reconstruction.
  • Management of hydrocephalus if present.

  

Encephalocele

• Definition: Herniation of brain tissue through a skull defect due to failed closure of the cranial neuropore.
• Types:
  • Occipital Encephalocele: More common in Western countries.
  • Frontal Encephalocele: More common in Southeast Asia.
• Treatment:
  • Surgical repair.
  • Address associated intracranial abnormalities.

Occult Spinal Dysraphism

• Signs:
  • Cutaneous markers over the lumbosacral area:
    • Hemangiomas
    • Hair tufts
    • Dermal sinus tracts
    • Lipomas
• Associated Conditions:
  • Tethered Cord Syndrome:
    • Symptoms: Back and leg pain, gait disturbances, weakness, orthopedic foot deformities, urinary and sexual dysfunction.
  • Diastematomyelia: Split spinal cord malformation. Neuro orthopedic syndrome
  • Dermal Sinus Tracts: Risk of infection due to skin connection to spinal canal.
• Treatment:
  • Surgical intervention to untether the cord and remove associated anomalies.

Chiari Malformations

• Type I:
  • Definition: Downward displacement of cerebellar tonsils through the foramen magnum.
  • Presentation:
    • Occipital headaches worsened by Valsalva maneuvers.
    • Foramen magnum compression symptoms: Cranial nerve dysfunction, cerebellar signs.
    • May have associated syringomyelia (cystic cavity within the spinal cord).
  • Diagnosis: MRI showing tonsillar descent.
  • Treatment:
    • Posterior fossa decompression.
    • Removal of part of occipital bone and C1 posterior arch.
    • Dural patch grafting to expand the dural space.
• Type II:
  • Definition: More severe hindbrain herniation associated with myelomeningocele.
  • Presentation:
    • Symptoms in infants: Stridor, dysphagia, apnea.
  • Treatment:
    • Surgical decompression.
    • Address associated myelomeningocele and hydrocephalus.

Craniosynostosis

• Definition: Premature fusion of one or more cranial sutures leading to skull deformities.

• Types:

  • Sagittal Synostosis: Most common; results in scaphocephaly (long, narrow skull).
  • Coronal Synostosis: Leads to brachycephaly (short, wide skull).
  • Metopic Synostosis: Causes trigonocephaly (triangular forehead).
  • Lambdoid Synostosis: Rare; must be differentiated from positional plagiocephaly.

  

• Treatment:

  • Surgical correction:

    • Resection of fused sutures.
    • Cranial vault remodeling.
    • Orbital rim advancement in syndromic cases (e.g., Apert, Crouzon syndromes).

    

    

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Central Nervous System Infections

CNS infections can be categorized based on their location:

• Intracranial Infections: Epidural abscess, subdural empyema, meningitis, brain abscess, ventriculitis.
• Spinal Infections: Vertebral osteomyelitis, discitis, spinal epidural abscess.

Intracranial Infections

Postoperative Infections

• Causes:
  • Commonly Staphylococcus aureus.
  • Also enteric organisms, Pseudomonas, Streptococcus species.
• Management:
  • Identify causative organism.
  • Administer appropriate antibiotics.
  • Surgical drainage if necessary.

Posttraumatic Meningitis

• Etiology:
  • Often due to CSF fistula following head injury.
  • Risk increases if leak persists >7 days.
• Clinical Signs:
  • CSF Rhinorrhea: Clear fluid from nose.
  • CSF Otorrhea: Clear fluid from ear.
• Management:
  • Surgical repair of fistula to prevent recurrent meningitis.
  • Antibiotic prophylaxis is controversial; decision should be individualized.

Cranial Epidural Abscess

• Location:
  • Commonly frontal (frontal sinusitis) or temporal regions (mastoiditis, ear infections).
• Etiology:
  • Contiguous spread from sinus or ear infections.
  • Post-traumatic (e.g., compound skull fractures).
• Clinical Features:
  • Local swelling, erythema, tenderness.
  • Signs of systemic infection.
• Diagnosis:
  • CT scan showing abscess and possible osteomyelitis.
• Treatment:
  • Surgical evacuation and debridement.
  • Drainage of infected sinuses.
  • Prolonged antibiotic therapy.
  • Possible delayed cranioplasty.

Subdural Empyema

• Definition: Collection of pus between the dura mater and arachnoid mater.
• Etiology:
  • Spread from paranasal sinus infections (frontal, ethmoid).
  • Retrograde thrombophlebitis.
• Clinical Presentation:
  • Fever, headache, meningeal signs.
  • Seizures, focal neurological deficits.
  • Altered mental status.
• Complications:
  • Cortical Venous Thrombosis: Can lead to infarction and rapid deterioration.
• Diagnosis:
  • Imaging shows subdural fluid collection with enhancement.
• Treatment:
  • Prompt surgical drainage.
  • Antibiotics. = 4-6 weeks
  • Anticonvulsants.
  • Steroids may be used.

Meningitis

• Definition: Infection of the meninges and subarachnoid space.
• Etiology by Age:
  • Neonates: Group B Streptococcus, E. coli, Listeria monocytogenes.
  • Children: Streptococcus pneumoniae, Neisseria meningitidis.
  • Adults: S. pneumoniae, N. meningitidis.
• Clinical Features:
  • Fever, headache, neck stiffness.
  • Altered mental status.
• Management:
  • Immediate CSF culture and antibiotic therapy.
  • Monitor for hydrocephalus; may require CSF drainage.
  • Investigate for CSF leaks in recurrent cases.

Brain Abscess

• Etiology:
  • Contiguous Spread: From sinuses, middle ear, mastoid.
  • Hematogenous Spread: From lungs, endocarditis, dental infections.
  • Unknown Origin: In about 20% of cases.
• Clinical Features:
  • Headache, nausea, vomiting.
  • Seizures.
  • Focal neurological deficits.
  • Signs of increased ICP.

• Diagnosis:

  • CT/MRI shows ring-enhancing lesion with surrounding edema.
  • Diffusion-weighted imaging and MR spectroscopy help differentiate from tumors.

  

• Complications:

  • Rupture into ventricles leading to ventriculitis.
• Treatment:
  • Surgical drainage or excision.
  • Antibiotic therapy tailored to organisms.
  • Anticonvulsants.
  • Steroids if indicated.

Ventriculitis

• Causes:
  • Commonly from shunt infections.
  • Can result from ruptured abscess or other infections.
• Management:
  • Drainage of infected CSF.
  • Intraventricular antibiotics.
  • Removal of infected shunt hardware.

Spinal Infections

Vertebral Osteomyelitis

• Etiology:
  • Hematogenous spread, often in IV drug users, diabetics, hemodialysis patients, elderly.
  • Commonly caused by S. aureus.
• Clinical Features:
  • Back pain.
  • Fever (may be absent in elderly).
• Complications:
  • Vertebral collapse.
  • Spinal instability.
  • Neurological deficits.
• Treatment:
  • Long-term antibiotics.
  • Surgical intervention if instability or neurologic compromise.

Discitis

• Definition: Infection of the intervertebral disc space.
• Association:
  • Often occurs with vertebral osteomyelitis.
• Clinical Features:
  • Severe back pain.
  • Fever.
  • Elevated ESR or CRP.
• Treatment:
  • Antibiotic therapy.
  • Immobilization.
  • Surgery if necessary.

Spinal Epidural Abscess

• Etiology:
  • Hematogenous spread or direct extension.
  • Risk factors similar to osteomyelitis.
• Clinical Features:
  • Localized back pain.
  • Radiculopathy.
  • Rapid progression to paralysis if not treated.
• Diagnosis:
  • MRI with contrast.
• Treatment:
  • Surgical decompression and drainage.
  • Antibiotics.
  • Possible conservative management in select cases without neurologic deficits.

CNS Infections in AIDS Patients

• Common Infections:
  • Toxoplasmosis:
    • Caused by Toxoplasma gondii.
    • Ring-enhancing lesions, often in basal ganglia.
  • Primary CNS Lymphoma:
    • Occurs in ~10% of AIDS patients.
    • Irregularly enhancing mass lesions.
  • Progressive Multifocal Leukoencephalopathy:
    • Caused by JC virus.
    • Non-enhancing white matter lesions.
  • Fungal Abscesses and Viral Encephalopathies.
• Management:
  • Antiretroviral Therapy: Reduces incidence of opportunistic infections.
  • Specific antimicrobial therapy based on the identified organism.

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Additional Notes

• Treatment Principles for CNS Infections:
  • Prompt identification and eradication of the causative organism.
  • Relief of mass effect if present.
  • Supportive care to manage symptoms and prevent complications.
  • Multidisciplinary approach involving neurosurgeons, infectious disease specialists, and critical care teams.
• Prevention:
  • Vaccinations (e.g., against Haemophilus influenzae, Neisseria meningitidis).
  • Early treatment of sinus, ear, and systemic infections.
  • Aseptic techniques in surgical procedures.
  • Monitoring and managing patients with known risk factors.